Casualties Mount as Gaza Conflict Wears On

Heavy fighting continued Monday in Gaza, with Israeli war planes bombarding more than 50 Hamas targets, Hamas firing as many rockets back into the Jewish state, and the death toll topping 500.

Israel reported hitting two weapons manufacturing sites and six underground rocket launchers on Monday. Hamas fired more rockets into Israel and tried to sneak fighters into the country in tunnels, but Israeli forces spotted the militants, killing 10 of them.

Developments in Gaza Conflict

July 8: Israel launches air strikes after rocket fire by Palestinian militants

July 10: President Obama says the United States is prepared to negotiate a cease-fire

July 16: Israel, Hamas agree to five hour cease-fire to allow civilians to restock and get medical care

July 17: Israel launches ground operation

July 20: U.N. Security Council holds emergency session after 100 Palestinians and 13 Israeli soldiers are killed in a day

July 21: U.S. Secretary of State John Kerry heads to Cairo for talks with Egyptian leaders on ways to end the fighting

July 23: Hamas says there can be no cease-fire until Israel ends blockade of Gaza

Palestinian officials said more than 500 Gaza residents have been killed by the Israeli attacks, including 25 in one home in a Sunday raid, all but one from the same family.

​"Twenty-five people! Doesn't this indicate that Israel is ruthless or not? Are we the liars? The evidence is here in the morgue refrigerators,” said Sabri Abu James, one of the survivors, in condemning the Israeli assault. “The evidence is in the refrigerators."

A total of 20 Israelis, including two civilians, have been killed since the offensive began July 8.

Overnight raids in Gaza killed several dozen Palestinians. Aside from the 10 fighters killed in the tunnels, at least 25 civilians were killed in a raid near Israel's southern border and another civilian was killed in Gaza City.

Sunday marked the deadliest day in the conflict, with more than 100 Palestinians and 13 Israeli soldiers killed.

Those soldiers all belonged to Israel's elite Golani Brigade, the AFP news agency reported. It said President Shimon Peres was expected to visit all their families to support them in their grief.

Obama expresses concern

U.S. President Barack Obama speaks about Ukraine at the White House in Washington, July 21, 2014.

President Barack Obama on Monday commented on the ongoing conflict in Gaza, saying that Israel has the right to defend itself against rocket and tunnel attacks from Hamas but that he has serious concerns about the rise in civilian deaths.

Obama said the U.S. and international focus is on bringing about a cease-fire that ends the fighting and stops the deaths of innocent civilians. The president added that Secretary of State John Kerry is traveling to Cairo to meet with allies and partners and help facilitate a cease-fire.

Obama stressed he does not want to see any more civilians killed in the conflict.

Israel intercepts 2 Hamas rockets

Also Monday, Israel's air defense system intercepted two rockets over Tel Aviv.

Israeli soldiers carry the coffin of Maj. Tzafrir Bar-Or, 32, at the military cemetery in Holon July 21, 2014.

Israeli Prime Minister Benjamin Netanyahu said Israel is "making every effort" to avoid civilian casualties. But, he warned they would continue as long as Hamas sustained its rocket attacks on the Jewish state.

"We are making every effort not to harm the residents, while Hamas is making every effort for the residents of Gaza to be harmed,” Netanyahu said. “We are sorry about every innocent person hurt. But as they are getting injured, Hamas is to blame and Hamas alone. "

Senior Palestinian official Yasser Abd Rabbo expressed concerns over the continued fighting. He said Palestinians want a cease-fire but also want to end the cycle that includes war and siege.

Gaza Strip

UN calls for immediate cease-fire

The U.N. Security Council has called for an immediate cease-fire. lt issued a statement late Sunday after holding an emergency session that Rwanda's ambassador and current Council President Eugene Gasana called "sobering." The council stressed the need to improve the humanitarian situation, including protecting civilians.

A cease-fire proposal by Egypt last week reportedly was accepted by Israel. But Hamas reportedly rejected it, saying it wanted a political solution to end the seven-year-old Israeli blockade of Gaza.

Diplomatic efforts to negotiate a cease-fire intensified as U.S. Secretary of State John Kerry flew to the region, joining U.N. Secretary-General Ban Ki-moon, who already had arrived.

Israel launched the offensive after hundreds of rockets were fired into its territory following the July 2 murder of a Palestinian teenager near Jerusalem. The teen was killed two days after the bodies of three abducted Israeli youths were discovered near Hebron in the West Bank. They had gone missing June 12.